In recent years, optical communication systems for optically interconnecting electronic devices such as computers, etc. and transferring information have been installed in offices, homes, etc.
Surface-emitting lasers are used as the light sources of such optical communication systems. A surface-emitting laser in a band of 850 nm has already been put to practical use for Ethernet (registered trademark) as high-speed LAN technologies (see JP-A No. 2005-093704).